RE: Preview: portable dumper

[Drew Adams]

> People expect to install one elc file and have it work in
> multple Emacs versions.

Would that it still were so.

> Only rarely have we made changes that would prevent this.

That used to be the case.  Now, nearly every major release is
incompatible, AFAICT.  As far as I can see, long gone are the
days when you could byte-compile in an older version and use
the byte-compiled code in a newer version.